The invention relates to a data transmission and recording system and more particularly to such a system designed to facilitate the exchange and recording of tactical military information between military units and to permit such information to be quickly and accurately plotted on maps. The system is interactive in that the information can flow in two directions, for example, from a higher echelon such as a command and control center to a field unit such as a company, using existing communications facilities; and other map information can be transmitted back to the command and control center using the same transmission facilities and the encoding apparatus of the present invention.
The system includes a processor module at the higher echelon which functions as an interface between the central processor of the higher echelon's computer and the communications system over which the map data is transmitted, and a field processor at the tactical field unit which interfaces with the communications channel and the stylus. The stylus is a device which is moveable by hand over the surface of an encoded map to locate the coordinates thereon at which data is to be plotted and for transmitting back to the processor module map information relating to tactical operations. The data sent to higher echelons is stored for later use and can be applied to display type maps and can be re-transmitted to other field units, if necessary, using the system of the present invention.
The incoming map data can be temporarily stored in the field processor and plotted at the field operator's convenience. The map data includes digitally coded map coordinates corresponding to the location on the map at which data is to be plotted. The maps are divided into a plurality of relatively large square map elements or mels and each mel is assigned a digital code according to its location along the x and y axes. The x and y coordinates of each mel are encoded on the back of the map in binary digital form, for example by printing two orthogonal codes thereon in magnetic ink. The stylus includes a coordinate code sensor which can read the mel codes as the stylus is moved over the map surface. The stylus is electrically connected to the field processor and it includes a digital display of the desired map coordinates. When the stylus has been moved to a proper coordinate, the display for that coordinate will indicate that the proper coordinate has been reached, for example by blinking.
Since greater resolution is desired than is practical with a hand-operated stylus and the relatively large mels, each mel is further subdivided into a plurality of sub-mels, and the system is designed so that the operator locates the proper mel as described above by hand, and then the proper sub-mel is located by means of a template and light emitting diode (LED) system attached to the stylus and electrically operated by several of the least significant of the binary digits read out of the field processor. This two stage system permits high resolution which would be otherwise impractical in a hand operated system.
The map coordinate sensors or transducers may take any one of numerous forms, however all comprise means to automatically sense the digital map mel codes and are capable of performing this function when moving across the map or when stationary. The underside of the stylus includes one or more magnets. The magnetic fields produced thereby are concentrated in the magnetic ink of the mel code bars to facilitate the reading thereof by the coordinate sensors.